1. Field of the Invention
The invention relates to the fields of flow detection, measurement and control. The invention also relates to fire suppression systems. In particular, the invention relates to multi-purpose piping systems for fire protection in structures and flow elements related thereto. The invention relates to systems for ensuring adequate circulation to fire protection sprinklers to minimize stagnation and/or freezing.
2. Description of the Prior Art
Practically any system where fluid flows in a conduit can use flow measurement devices. There are any many different kinds of flow measurement devices as there are systems where fluids flow in a conduit (such as a typical pipe). For example, it is well known that there is a pressure drop across an orifice plate, and that this pressure drop can be used to determine the fluid flow through the pipe. The pressure drop is proportional to the velocity of the fluid in the pipe. As another example, a positive displacement device may be placed in a conduit, which directly measures the volume of fluid flowing therethrough. From the known volume measured by the positive displacement device, the velocity of the fluid in the pipe can be determined. An example of this type device is a paddle flow switch commonly used in fire protection systems. Each type of flow measurement device has its strengths and weaknesses, and may be applicable to one system, while not being suitable for another.
Check valves (single and double acting) are also widely used in systems where fluids flow in conduits. The purpose of a check valve is to allow flow in one desired direction, but prevent flow in the opposite undesired direction. Existing check valves often use a moving seat, which is forced open by fluid flowing in the desired direction, but which moving seat is sealingly forced against an annular shoulder, preventing flow in the undesired, opposite direction.
It is well known to use electronic sensor means to transmit a signal generated by a flow measurement device to a read out or alarm means. The electronic output may be generated in response to a pressure transducer or the like. There are a myriad of ways to generate an electronic signal proportional to flow of a fluid in a conduit. As with our orifice plate noted above, the differential pressure is proportional to the flow in the conduit. Therefore, a differential pressure transducer exposed to the up stream and down stream fluids would produce an output electrical signal proportional to the flow of fluid through the conduit. In the paddle flow switch, the volume between the paddles is known, and a signal is generated indicating the number of revolutions per unit time of the paddle, thus allowing calculation of the flow velocity. Vane-type paddle flow switches are typically used in the fire protection industry.
It is also well known to provide a bypass means for allowing fluid flow around a restriction, in certain circumstances. For example, for use in a multi-purpose piping system, it made be desirable to divert flow around a water softener where the demand for water in the residence for fire protection is greater than is able to flow through the water softener. As another example, in a chemical process, chemicals may be passed through a reactor unit. However, should the reactor become plugged or otherwise unduly restrict the flow, it may be desirable to bypass the reactor so as to prevent damage to the reactor vessel and/or a process upset. In these circumstances, it is necessary to have a bypass means which can divert flow around the flow element causing the pressure drop in certain circumstances.
In most fluid flow systems, each of the above noted flow elements (flow measurement, check valve, bypass means) is a separate fitting which must be placed in the fluid system. It is often desirable to combine as many of the above noted functions into one device as possible. The combination of multiple devices, for example the flow meter, check valve, and means for converting a fluid flow to an electronic out put signal, are obvious. A reduced number of devices reduces complexity, cost, and difficulty of installation of a fluid flow system.
It is also well known to provide a means for enunciating an alarm when water flows through a fire protection system. Typical commercial fire protection systems do not have significant water flow therethrough unless a sprinkler head is activated by a fire. Thus, the typical commercial system need only to detect whether or not flow is present, and if so, an alarm must be enunciated.
In application Ser. Number 09/098,976 filed on Jun. 1, 1998, for an Apparatus And Method For Multi-purpose Residential Water Flow Fire Alarm, a method was disclosed which allows the same piping to be used for both domestic and fire protection needs. The method provided for a flow detection and measurement means which is capable of distinguishing typical domestic flow from fire protection flow caused by the operation of one or more sprinkler heads.
The National Fire Protection Association ("NFPA" ) has established standards for the design and operation of multi-purpose residential fire sprinkler systems. The standard is known as NFPA 13D, 1999 Ed. It defines a multi-purpose piping system ("MPS" ) "piping system within dwellings and manufactured homes intended to serve both domestic and fire protection needs."
Typical commercial fire sprinkler systems utilize a water flow detector to provide an alarm means. When a flow of sufficient, minimal, volume is detected, typical commercial systems indicate an alarm condition. The only reason that water typically flows in commercial systems is activation of a sprinkler head. Therefore, in a typical commercial system an alarm means need only determine whether or not water is flowing. Paddle flow switches are commonly used to determine when flow occurs in commercial systems. As noted above, these are typically vane-type paddle flow switches.
In the MPS water regularly flows through the common piping. Flows occur to supply domestic needs within the residence. Whenever a sink, shower or toilet valve open, water flows in the MPS. Therefore, the alarm system used on typical commercial applications will not work for the MPS because simply taking a shower might cause a typical commercial flow detector to alarm when used with the MPS.
In light of this problem, typical residential applications have two completely different piping systems: (1) a fire sprinkler piping system, and (2) a domestic piping system. This basically doubles the number of pipes and the amount of plumbing work which has to be performed in a typical residential application. The same set of piping could not previously be used for both systems because the flow alarm could send false signals when domestic water was turned on. Alternatively, a residential application could use a fire detection system (i.e., smoke detector system). However, a smoke detection system does not alarm when water flows. Therefore, with a smoke detection system and no flow alarm, the fire sprinklers could run for days, causing extensive water damage, while the home owner is away on vacation and no alarm would sound. Also, smoke detection systems are expensive.
As noted above, U.S. patent application Ser. No. 09/098,976 filed Jun. 1, 1998, disclosed an Apparatus And Method For Multi-Purpose Residential Water Flow Fire Alarm. The apparatus for use as a multi-purpose residential fire suppression water flow alarm system disclosed in that application was comprised of a supply side for delivering water under pressure; a multi-purpose piping system having a system side with common piping for delivering water from the supply side to a fire suppression side with one or more sprinkler heads and a domestic side for one or more domestic uses; a detecting means for detecting fire protection flow and for distinguishing that flow from a maximum domestic flow, the detecting means being disposed between the supply side and the system side; a drain test connection; and an alarm means. The method of utilizing the apparatus described above was also disclosed. One of the dependent claims from the above-noted application, claimed a detecting means comprised of an orifice plate through which water flows causing a differential pressure measured by a differential pressure switch so that the flow rate to the orifice plate is proportional to the differential pressure allowing a determination of flow rate based on the differential pressure measured.
It was disclosed that the flow detection means could utilize any number of well known flow measurement technologies, such as U.S. Pat. No. 5,288,469 to Otten et al. The Otten device incorporates both an orifice plate and a cone-shaped plug around which the water flows. U.S. Pat. No. 5,419,203 to Carmichael discloses a device similar to the device disclosed by Otten. Otten utilizes the Hall effect to measure the displacement of a displacement piston having incorporated therein a magnet. Carmichael utilizes strain sensors to measure the strain caused by displacement of a cone-shaped plug biased by a spring member. As the flow increases, the cone-shaped plug displaces backwardly in reaction to the flow putting greater pressure on the spring and consequently, greater pressure on the pressure sensors incorporated in the device. The Otten and Carmichael devices have several common features, namely a chamber having an orifice plate and a plug-shaped device adapted to be deflected away from the orifice plate in proportion to the flow rate through the chamber. The flow measurement means must be simple in both operation and concept so that it will be inexpensive to build and can be easily programed and calibrated in the field. The problem with Otten and Carmichael is that their devices allow flow therethrough the instant pressure is applied across the orifice plate. As disclosed, they are not capable of serving as a bypass means for allowing flow only when the differential pressure exceeds some preset level.
Critics of the MPS have also noted that it is common for residential systems to incorporate a water softener or similar devices (such as filters, chlorination systems, UV purifiers and the like). Water softeners and similar devices can create substantial drops in system pressure such that the water supply flowing through a typical residential system may not be sufficient for fire protection needs. Therefore, there is a need for a bypass mechanism which will allow sufficient flow in fire protection situations to bypass the water softener to supply the fire protection needs.
Prior art systems also suffered from problems with freezing. Where lines were in locations that could reach temperatures below freezing, it was a common problem to face freezing in the pipes, which could crack sprinkler heads and/or piping systems. Prior art systems addressed this problem in a number of ways, including dry pipe systems, which do not have any water in the piping until fire is sensed, by placing pipes in locations where they were not exposed to cold temperatures (for example, by placing insulation wrap over piping systems in favor of heated spaced below) and the like.
In prior art systems, typically, city water or other supply means are connected to a supply system leading into a structure. Water typically first flows through an outside gate valve. The gate valve is typically integrally connected with a water meter, though the two parts may be completely separate. After flowing through the gate valve and meter the water passes an exterior wall of the structure. A main control valve is provided in case it becomes necessary to shut off all the water in the structure. Though shown inside the structure the main control valve may also be outside. A pressure gauge may be provided to monitor water pressure in the system.
Where there are both domestic uses and a fire sprinkler system, a flow splitter divides the water supply into two distinct streams: (a) a fire side, and (b) a domestic side. Following the flow splitter a flow detection means is provided on the fire side. The flow detection means is coupled to an alarm means. Upon detection of flow by the flow detection means, a signal is sent to the alarm means, which creates an alarm condition therein. Piping leads away from the flow detection means to a drain/test connection. The drain/test connection serves two purposes: it allows the fire side to be drained, and it allows for simulation of the flow rate created by the operation of a sprinkler head. Piping also leads away from the flow detection means to at least one sprinkler head. A separate set of piping, the domestic side, leads to one or more domestic uses.
It is known that domestic uses of water can have a high enough flow rate to detract from fire protection needs. Therefore, the prior art also discloses a domestic water supply shut-off valve, which is effectively incorporated into the flow splitter for shutting off water supply to the domestic side. Such a shut-off valve is illustrated by U.S. Pat. No. 5,236,002 to Martin, et al. A typical National Fire Protection Association ("NFPA 13D" ) system requires two complete sets of piping, both fire side piping and domestic piping to be run throughout the structure. These two pipes running side by side require substantial increased material and labor costs to install. Further, for an existing structure, it may be extremely expensive or even impossible to install the second set of piping required for a fire sprinkler system.
The NFPA allowed the MPS because, in their estimation, the cost savings associated with single systems instead of duplicate systems, would cause the MPS to be installed in more homes, thus saving more lives. However, the NFPA provides no means for alarming upon a water flow condition in the MPS, which is a system where both domestic and fire protection systems use common piping.
With the MPS, again, a city or other domestic water supply is provided. The water flows through the outside gate valve and water meter through the outer wall of the structure. Thence the water flows through the main control valve. A pressure gauge is typically provided to monitor water pressure in the system. No flow splitter is required for the MPS. There is no flow detection means with the MPS. As noted above, typical flow detection means alarm upon detection of a minimum flow. Therefore, given the common piping system in the MPS, typical domestic uses could cause the prior art flow detection means to send an alarm signal to the alarm means. NFPA provided for installation of a non-water-flow-based smoke detection and alarm system for use with the MPS. These non-water-flow-based smoke detection and alarm systems are expensive, and they are not capable of detecting flow through one or more fire protection sprinklers. The inability of a smoke detection system to detect and enunciate a water flow alarm could result in extensive water damage to the property.
Parent Applications
The parent applications (Ser. Nos. 09/483,999 and 09/098,976) disclosed the MPS with a water flow alarm. Since they envisioned the MPS, common piping carried water throughout the system. After passing through the main control valve, water passed by a pressure gauge, then through a flow detection means. In combination the flow detection means and the pressure gauge allowed for determination of whether the water supply is sufficient for fire protection needs. The flow detection means was connected to an alarm means which activated upon the detection of a flow rate greater than maximum domestic flow. Methods of detecting and measuring flow and alarming upon excessive flow are illustrated, for example, in Otten, et al., U.S. Pat. No. 5,228,469. Disposed after the detection means was a drain test connection. This drain test connection served the same purpose as it did in the prior art. The drain test connection also preferably included an orifice plate with interchangeable orifice plates for simulating different flow regimes. For example, one orifice plate could simulate the operation of a single fire sprinkler while another orifice plate simulated the domestic usage. These interchangeable orifice plates could then be used to calibrate the operation of the alarm means. Common piping carried water throughout the system to both domestic and fire protection uses. Rather than having distinct fire sides and domestic sides, the Parent Applications disclosed short sections of pipe split off from the common piping which were designated as either fire side or domestic side.
The Parent Applications also disclosed a flow sensor incorporating a combination orifice flow meter/displacement magnetic flow sensor in an annular housing. The annular housing was preferably be composed of a non-magnetic, metallic material, such as aluminum. Alternatively, the annular housing could be comprised of a polymer such as CPVC or similar materials. The material of construction was not critical so long as it did not interfere with the magnetic activation of the Reed switch. The annular housing had two ends, and at each end a bushing or reducer adapted to be threadedly (or by a socket) attached thereto to allow connection of an inlet pipe at an inlet end of the annular housing and an outlet pipe at an outlet end of the annular housing. A moving orifice plate, having a front face and a back face, was adapted to be received within the annular housing. The annular housing had at least one section with a continuous diameter defined therein for receiving the moving orifice plate. The moving orifice plate had a diameter which was slightly smaller than that of the continuous diameter section of the annular housing, allowing a sliding motion therein, but preventing excess fluid to flow around a periphery of the moving orifice plate. A moving plate opening was defined at or near the center of the moving orifice plate. An orifice plate magnet flange having a diameter larger than that of the moving plate opening was disposed on a back face. Disposed substantially around and outside the flange was a circular orifice plate magnet. The moving orifice plate was biased away from the outlet end by a orifice plate spring. The orifice plate spring was contained between an interior flange shoulder near the outlet end, and the orifice plate magnet. Mounted on an exterior portion of the annular housing was a Reed switch. The Reed switch was attached to the annular housing by an adjustable attachment means. Adjustment screws held the adjustable attachment means in place and allowed it to be loosened for movement of the Reed switch for calibration of the device.
The Parent Applications also disclosed another related embodiment of the combination orifice flow meter/displacement magnetic flow sensor. This embodiment was adapted to be used in systems where a water softener or similar pressure drop causing device is present. The outlet to the water softener was on the supply side of the sensor, and the inlet from the water softener was on the system side of the sensor. A "bullet rod" was held in place by a bullet port within the annular housing. The bullet port was comprised of an outer annular ring held in place between an annular shoulder and a bushing, support legs projecting inwardly from the annular ring, and an inner support ring. An open port area was defined between each of the support legs. Preferably, the sum of the open port areas was at least as large as the cross sectional area of the inlet pipe connected to the sensor, thus, the pressure drop through the device was minimized. A bullet rod having a head portion with a leading end and a threaded male end adapted to be received through the inner support ring was provided. A tail portion had a threaded female end adapted to threadedly engage the male end, so that the tail portion is held in place against the inner support ring. The tail portion also had a tapered end. The tapered end faced the outlet end of the sensor. The moving orifice plate opening was sized to receive the tail portion so as to allow sliding motion of the moving orifice place and also to minimize flow between the tail and the orifice plate. Thus, as the moving orifice plate was displaced toward the outlet end by differential pressure, substantially all of the flow was diverted through the water softener until the differential pressure displaced the orifice plate past the tapered end, at which point water flowed through the orifice in the orifice plate. As discussed below, preferably two Reed switches were provided, the first for a trouble alarm, and the second for enunciating the alarm means.
To reiterate, the problem to be solved by the Parent Application was provision of a water-flow-based means of alarming the MPS. In the past, such systems had to utilize two completely different piping systems: one for domestic uses and one for fire sprinkler system uses. Previous alarms used in these systems were designed to create an alarm condition upon the detection of a flow (commonly 8-10 gpm). Typical domestic flows could have caused an alarm in a prior art system. Alternatively, prior art systems used a smoke detection and alarm system which did not have a flow detector. These systems without a flow detector risked substantial water damage to the structure if a sprinkler head activated while no one was in the home.
The Parent Applications used the principle that domestic flow rates are much lower than flow rates needed for fire protection. Using a flow detection means, it was possible to create an alarm condition only upon detection of flows which are such as created by fire protection needs. Thus, an alarm condition was not created when typical domestic uses only were detected.
Preferably, the Parent Applications also incorporated a tamper detection means on the main control valve. The tamper protection means determined whether the main control valve was closed, and if so, enunciating a trouble alarm. A pressure gauge was also preferably provided in the system.
The combination orifice flow meter/displacement magnetic flow sensor disclosed in the Parent Applications preferably had two normally open Reed switches disposed thereon for detecting flow as indicating by displacement of the moving orifice plate. The first Reed switch was the same as previously disclosed, and enunciates a fire alarm via the fire alarm means. Preferably, the first Reed switch also activated a system which contacts emergency response personnel, such as fire departments. In addition to the fire alarm Reed switch, a second Reed switch may be provided. The second Reed switch enunciated a first stage "trouble alarm". Preferably, the first stage trouble alarm only enunciated within the structure (i.e., emergency response personnel were not contacted). The trouble alarm was created if the domestic usage was excessive. Where the system was used with the MPS, the first stage alarm would naturally cause anyone in the residence to instinctively shut off water, for example a shower they may be taking. As another example, if a resident heard a first stage alarm, and they were washing dishes, they would most likely shut off the sink faucet. This natural reaction to the first stage alarm may reduce the water flow demand below the level where the first stage alarm enunciates, eliminating the alarm condition. The first stage Reed switch is displaced a slight distance toward the inlet of the flow sensor relative to the fire alarm Reed switch. Thus, as the moving orifice plate is displaced towards the outlet end of the flow sensor, it will first activate the first stage Reed switch, enunciating the internal first stage trouble alarm. As the orifice plate continues to be displaced towards the outlet end, it will next activate the fire alarm Reed switch, which enunciates the alarm means, preferably notifying emergency response personnel. The relative linear displacement of the fire alarm Reed switch and the trouble Reed switch was to be set in the field so that there was sufficient differential in the flow which activates the first stage alarm and the fire alarm to give residents or occupants of the structures sufficient time to shut off domestic demands before a fire alarm is created. This two-stage system also serve as a safety back up, because if one of the alarm stages fail, the other still alerted residents to the potential alarm condition.
Tamper detection means on the main control valve preferably incorporated Reed switches as well. As the handle was turned, a magnet on the handle activated a normally open Reed switch, causing it to close, enunciating an alarm notifying the occupants of the structure that the main control valve had been closed, and the fire protection system was not being supplied with water. Again, this is an important safety consideration in residential systems where small children, unknowing homeowners, and the like can easily turn off the system without realizing they are shutting off their fire protection system as well.
Though the Parent Applications described the inventions therein with reference to a multi-purpose piping system, it should be understood that the system could be used with any flow-based system. Further, the flow detection means disclosed herein could be used with any flow system, not just fire protection systems. That is, the flow detection means are capable of detecting the flow of any fluid through a piping system. The piping system could carry hydrocarbons, solvents, or any other liquid or potentially gaseous materials for that matter.
In operation the apparatus disclosed in the Parent Applications functioned as both a domestic water supply system and a smoke detection and alarm system. Under normal conditions, the water flow rate through the flow detection means did not reach the fire suppression flow rates. When one or more sprinkler heads activated, the flow detection means detected the increased flow and sent an alarm to the alarm means. The alarm means enunciated a visible and/or audible alarm indicating the alarm condition. It is well known in the prior art to activate a telephone modem-based system for calling, for example, the fire department, upon detection of an alarm condition. See, e.g., Otten, U.S.
Pat. No. 5,139,044. It was preferable to incorporate such a modem-based component in the present invention to notify the fire department and other emergency contacts should a fire alarm condition be detected. If one or more domestic cutoff valves were included in the apparatus, the flow detection means also sent a signal to activate the domestic cutoff valves, shutting off water to one or more domestic uses and providing more water for the fire sprinklers.
When the two-stage alarm system was provided, it was necessary to calibrate both the first stage trouble alarm and the first stage Reed switch. The preferred method was to first calibrate the fire alarm Reed switch. The calibration was very simple. First, the drain test connection is opened to simulate fire protection needs, the connection means for the Reed switch were loosened, and it was moved towards the inlet end of the sensor until an alarm condition was created. The first stage Reed switch was then moved a slight distance further towards the inlet end. A typical domestic demand was then created by using the drain test connection or flowing water from some number of plumbing fixtures. As the flow through the drain test connection exceeds the high end of the expected domestic demand, the first stage Reed switch should be activated, activating a first stage trouble alarm. If the alarm is not activated, the first stage Reed switch is moved further towards the inlet end of the sensor.
Shortcomings of the Prior Art
In prior systems it was often necessary to provide both a double check valve element and a flow detection/measurement/control sensor. Both of the elements increased the cost of this system and increased the pressure drop through the system. There was a need for a flow sensor that could both serve as a double check and as a flow detection or measurement means.
In multi-purpose piping systems, as well as stand-alone fire protection systems, there was the problem of stagnation (where water was to be used for human consumption) of water in the piping as well as the problem of freezing, where piping was exposed to temperatures lower than 32.degree. Fahrenheit. Freezing presented itself as attic of a residence. There was therefor a need for a system which provides for the warming of pipes to prevent freezing, as well as circulation through the pipes to prevent stagnation.
Another problem that plagued prior art systems was the issue of retrofitting existing structures for fire protection systems. Retrofitting for a fire protection system in a typical structure would be very expensive because, where the freezing issue is a problem, piping would have to be installed in conduits below the ceiling of the structure (or at least under insulation) to prevent the danger of freezing.